The continuing need to conserve water resources has lead to increasing pressure on manufacturers of sanitary ware to reduce the amount of water used by these devices. This in turn has lead to the development and increasing deployment of so-called waterless or water-free urinals. These fixtures typically have a vertical wall or backsplash joined to side walls. The interior surfaces of these walls will be referred to herein as the non-wetted surfaces of the urinal. While the backsplash and side walls do get wet during use, they are not permanently bathed in fluid and they have the potential to dry off, thus the term non-wetted surfaces. The backsplash and side walls converge at the bottom of the urinal to form a bowl. A drain or sewer pipe is connected to an opening in the bowl. The interior of the bowl defines a well which retains a quantity of liquid therein covering the drain pipe to prevent escape of gases from the drain pipe. A trap or cartridge is typically disposed in the bowl. The trap defines a circuitous path for liquids to pass through the bowl, eventually overflowing a trap opening into the drain or sewer pipe.
A trap sealant fluid having a specific gravity lesser than that of urine is provided in the well where it resides on top of a charge of water or a water/urine mixture. The trap sealant prevents exposure of the urine to the ambient air, thereby preventing formation of foul odors from the urinal. The trap sealant is a fluid that does not readily mix with urine but instead floats on top and permits urine to flow through it and into the passages of the trap. The interior portions of the bowl that are permanently in contact with the urine and sealant will be referred to herein as the wetted surfaces because in normal operation they are always in contact with fluid and are never permitted to dry off.
Examples of the general structure of a waterless urinal as just described are shown in U.S. Pat. Nos. 6,701,541, 6,589,440 and 6,286,153.
One of the problems with existing waterless urinals is they require a relatively high level of maintenance to replenish the trap sealant and clean the non-wetted surfaces. While the sealant in general does not mix with urine and floats on top of it in the well, the natural turbulence of flow when urine enters the well will entrain small amounts of the sealant with the urine and carry it into the drain. Thus, the level of sealant gradually diminishes. Manual replenishment of the sealant is required for the prior art waterless urinals to operate properly.
Another problem with prior art waterless urinals is in many operating environments the usage rate of the urinals is such that the backsplash and side walls eventually dry out. While the trap is designed such that much of the well portion of the urinal is covered by the sealant fluid, that is not the case for large portions of the fixture. Objectionable odors result from the alternating wetting and drying of the backsplash and side walls. Naturally these odors lead to complaints of unsanitary conditions. Of course, conventional water-flushed urinals avoid this problem by running water down the fixture at each flush cycle, or at least some of the flush cycles. Some water-flushed urinals have attempted to reduce their water consumption by reducing the number of backsplash rinse cycles or the amount of water used in each one. See U.S. Pat. Nos. 5,235,706 and 6,862,754. However, none of these efforts are adaptable to waterless urinals.